The present invention relates to an oscillating motor according to the preamble of claim 1.
Such oscillating motors are employed in particular in aircraft and motor vehicle industries.
Such oscillating motor comprises a stator with a casing and covers on two sides. One or several stator wings are disposed in the casing. A driven shaft is supported in the covers, wherein the driven shafts are equipped with rotor wings in equal numbers. The stator wings and the rotor wings form several volume changeable chambers, which are formed as pressure chambers or, respectively, discharge chambers and which are correspondingly furnished with a connection to the corresponding feed port or, respectively, discharge port. The pressure chamber and the discharge chambers are separated from each other by in each case one frame sealing element surrounding the stator wing or, respectively, the rotor wing. In each case a ring shaped sealing element is disposed in the region of the driven axis between the rotor and each cover and preferably in the cover for sealing against the outside.
Oscillating motors of this kind are subject to large sealing problems, which are expressed in a very high wear of the sealing elements and in an unsatisfactory sealing quality in the region of the driven shaft not at last because of the limited and alternating rotary motion.
Already many attempts have been undertaken for resolving this problem. For example it is known to employ a flexible diagonal sealing ring, wherein the flexible diagonal sealing ring is inserted into an anullar groove of the cover and is aligned with its diagonal sealing edge opposite to the pressure direction onto the circulating sealing slot between the front faces of the cover and the rotor wing. Pressure medium passes into the hollow space of the diagonal sealing ring through this sealing slot during operation, wherein a pressure equal to the pressure in the pressure chamber builds up in the hollow space of the diagonal sealing ring, wherein the pressure presses the flexible diagonal sealing ring with its sealing edge against the circulating sealing slot based on different face ratios and closes the circulating sealing slot. This sealing variation, however, is associated with substantial disadvantages. A very high wear occurs at the diagonal sealing ring, since the resting diagonal sealing ring is subjected to different pressure loads and is pressed continuously against the rotor moving in alternating directions. This leads because of the high load to a small lifetime of the diagonal sealing rings and thus to an increase in expense of the oscillating motor. A further disadvantage comprises that the enclosed pressure remains present in the hollow spaces of the diagonal sealing ring even in case of a pressureless pressure chamber. A still higher friction force occurs relative to the operating state in the resting state based on the different pressure situations, wherein the still larger friction force has to be overcome always with each starting up of operations. This again contributes to a decrease in the lifetime and furthermore limits seriously the application field of such oscillating motors because of the bad starting behavior.
It is also known to employ a sliding sealing ring in the cover instead of the diagonal sealing ring, wherein the sliding sealing ring rests against the rotating front faces of the rotor wings and thus at the sealing element of the box. The frame sealing element is severely loaded by an unintended but always possible relative motion between the sliding sealing ring and the frame sealing element at the rotor wing, which is associated with a short lifetime. In addition, the sealing values are extremely low under use of the sliding sealing ring, which decreases the degree of effectiveness of the oscillating motor. The possibilities of employment of this oscillating motor are substantially limited based on the small degree of effectiveness and the small lifetime duration of the anullar sealing elements.
It also became known from the U.S. Pat. No. 3,426,654 to employ a diagonally acting sealing element, which is loaded by a flexible sealing ring in sealing direction and is supported in its sealing function by the flexible sealing ring. Finally also this sealing variant cannot do justice to the high requirements with respect to the start-up behavior, the sealing effectiveness and the lifetime.
Therefore it is an object, to improve the start-up behavior in case of radial oscillating motors of the present kind and to maintain the high standard in the sealing function and the lifetime in this situation.
This object is accomplished with the characterizing features of claim 1. Useful embodiments result from the sub-claims 2 through 7.
The invention eliminates the recited disadvantages from the state of the art. In particular the start-up behavior of the oscillating motor is thereby improved such that the static pressure enclosed in the incorporation chamber of the diagonal sealing ring and the dynamic work pressure present in the pressure chambers can be balanced through pressure balancing channels to both sides of the sliding sealing ring. This reduces the undesired press-on forces operating during resting and during working of the oscillating motor by an advantageous order of magnitude. It is here of advantage to balance both the static pressure from the incorporation chamber of the diagonal sealing ring as well as the dynamic pressure part of the pressure chambers at the sliding sealing ring. It is assured with the locking piston or securing means against rotation between the rotor and the sliding sealing ring such that the sliding sealing ring performs a relative motion to neither sealing element nor to the frame sealing element nor to the diagonal sealing ring. Here a static sealing position is realized, which is characterized by a high capability of sealing. This static sealing position means in addition, however, a very gentle treatment of the concerned sealing elements, which results in a high lifetime. It is a particular advantage if separated anullar channels are furnished for the dynamic pressure balance and for the static pressure balance. This allows an always constant press-on force at the sliding sealing ring.